Geometric center of open polyline, line

[maahee]

(setq gct (osnap (vlax-curve-getStartPoint bm) "gcen"))

The above code line gives only closed polyline

How to find the geometric center of an open polyline and a single line

[DATVO]

1 hour ago, maahee said:

(setq gct (osnap (vlax-curve-getStartPoint bm) "gcen"))

The above code line gives only closed polyline

How to find the geometric center of an open polyline and a single line

 

Only the geometric center is available for closed areas, since open polylines have no area and therefore no true center. If it’s just a line, the "geometric center” is the midpoint. 

[Saxlle]

You can actually calculate it, here is the code (you can change it for your purposes):

 

(setq ptlist (mapcar 'cdr (vl-remove-if-not (function (lambda (x) (= (car x) 10))) (setq ent (entget (car (entsel "\nSelect the line:")))))) ;; point list
      sum_x 0
      sum_y 0
      vertices (cdr (assoc 90 ent)) ;; number of vertices for LWPOLYLINE
      )

(foreach pt ptlist
  (setq sum_x (+ sum_x (car pt))) ;; sum only the X vertices values
  )

(foreach pt ptlist
  (setq sum_y (+ sum_y (cadr pt))) ;; sum only the Y vertices values
  )

(setq sum_x (/ sum_x vertices) ;; dividing the total sum X by the number of vertices
      sum_y (/ sum_y vertices) ;; dividing the total sum Y by the number of vertices
      pt (list sum_x sum_y) ;; geometric center
      )

 

Below are the pictures with geometric center for open and closed polyline (picture 1 open, picture 2 closed).

 

Picture 1.

 

Picture 2.

 

50 minutes ago, DATVO said:

If it’s just a line, the "geometric center” is the midpoint. 

 

This is true.

 

Best regards.